Lecture 2: Inflammation and Repair Flashcards
Based on Robbins Outlines
Asthma (chronic and acute) is due to what immune cells?
Eosinophils, IgE Abs
Glomerulonephritis is due to what cells?
Acute or chronic?
- Abs and complement, neutrophils, monocytes
- Acute
Septic shock is due to what cells?
Acute or chronic?
- Cytokines (cytokine storm)
- Acute
Arthritis is due to what cells?
Acute or chronic?
- Lymphocytes, macrophages
- Chronic
Atherosclerosis is due to what cells?
Acute or chronic?
- Macrophages, lymphocytes
- Chronic
Pulmonary fibrosis is due to what cells?
Acute or chronic?
- Macrophages, fibroblasts
- Chronic
What kind of inflammation is characterized by the following: mostly neutrophils, prominent local and systemic signs, mild and self-limited tissue injury, fibrosis.
Acute inflammation
Primary granules (azuorphilic) of neutrophils contain what?
How are they described?
- MPO, bactericidal factors (lysozyme, defensins), acid hydrolases, and variety of neutral proteases (elastase, cathepsin G, non-specific collagenases, proteinase 3)
- Larger
Secondary (specific) granules of neutrophils contain what?
Described as what?
- Lysoszyme, collagenase, gelatinase, lactoferrin, histaminase, and alkalne phosphatase
- Smaller
Cells express receptors in what 3 places which allows them to sense the presence of foreign invaders in any cellular compartment?
- Plasma membrane for extracellular microbes
- Endosome for ingested microbes
- Cytosol for intracellular microbes
Sensors of cell damage can detect what molecules?
- Uric acid (DNA breakdown)
- ATP (damaged mitochondria)
- Reduced intracellular K+ (loss of plasma membrane integrity)
- DNA
Gain of function mutations in the sensors for cell damage cause rare diseases known as _______ and they are treated with _________.
Gain of function mutations in the sensors for cell damage cause rare diseases known as autoinflammatory syndromes and they are treated with IL-1 antagonists.
What are the 3 major components of acute inflammation?
1) Dilation of small vessels leading to an increase in blood flow
2) Increased permeability of the microvasculature enabling plasma proteins and leukocytes to leave circulation
3) Emigration of the leukocytes from the microcirculation, their accumulation in the focus of injury, and activation to eliminate the offending agent
Escape of fluid, proteins, and blood cells from the vascular system into the interstitial tissue or body cavities is known as?
What is found in high concentrations in this fluid?
Inflammatory or non-inflammatory edema?
- Exudation = inflammatory edema
- High protein
A fluid with low protein content (most of which is albumin) with no to little cellular debris and low specific gravity - essentially an ultrafiltrate of blood is known as?
Inflammatory or non-inflammatory?
Produced as a result of?
Examples of disease?
- Transudate = non-inflammatory ededma
- Osmotic or hydrostatic imbalance across the vessel wall without an increase in vascular permeability
- CHF increases hydrostatic pressure due to venous outflow obstruction
- Liver disease causing decreased protein synthesis or kidney disease causing increased protein loss = decreased colloid osmotic pressure
What is the source of histamine?
Action?
- Mast cells, basophils, platelets
- Vasodilation, increased vascular permeability, and endothelial activation
The increased vascular permeability seen with acute inflammation happens where specifically?
Post-capillary venules
*Hallmark of acute inflammation
Inflamed lymph nodes are often enlarged because of ______ of the lymphoid follicles and increased number of lymphocytes and macrophages
Hyperplasia
Blood flow slows early in inflammation (stasis), hemodynamic conditions change (wall shear stress decreases), and more white cells assume a peripheral position along the endothelial surface. This process of leukocyte redistribution is called?
Margination
Tissue macrophages, mast cells, and endothelial cells that encounter microbes and dead tissue secrete which cytokines that act on the endothelial cells of post-capillary venules adjacent to an infection?
Which selectin and ligand are expressed first?
- IL-1 and TNF
- E-selectin
- Ligand for L-selectin
Histamine and thrombin stimulate the redistribution of __-selectin from its normal intracellular stores in endothelial cell granules called?
- P-selectin
- Weibel-Palade bodies
*Mnemonic: Weibel-Palade == W-P == vWF and P-selectin
Red streaks near a wound is a telltale sign of?
Streaking follows the course of the lymphatic channels and is diagnostic of; may be accompanied by painful enlargement of draining lymph nodes, indicating?
- Sign of infection in the wound
- Lymphangitis: inflammation of lymph vessels (red-streaks)
- Lymphadenitis: inflamed, often enlarged lymph nodes (lymphadenapothy)
What integrins are converted into a high-affinity state upon activation of the cell?
VLA-4 and LFA-1 on the leukocytes
What is the source of PGs?
Action?
- Mast cells, leukocytes
- Vasodilation, pain, fever
IL-1 and TNF induce endothelial expression of ligands for integrins, what are the 2 main ligands and their corresponding integrins on the leukocytes?
- VCAM-1 (CD106), the ligand for β1 integrin VLA-4
- ICAM-1 (CD54), the ligand for β2 integrin LFA-1 and Mac-1
What are the ligands for the selectins?
Sialylated oligosaccharides bound to mucin-like glycoprotein backbones (Sialyl-Lewis X)
What is the adhesion molecule present in the intercellular junctions between endothelial cells that’s part of the Ig superfamily, where is it found and what is its ligand?
- CD 31 (PECAM-1)
- Endothelial cells AND leukocytes
- Ligand = CD31 (PECAM-1) = homotypic interaction
What is the most common exogenous chemoattractant and the endogenous chemoattractants?
Exogenous: N-formylmethionine
Endogenous: IL-8, C5a, Arachidonic acid metabolites, mainly LTB4
Chemoattractant agents bind to what kind of receptors on leukocytes?
Activate which second messengers?
Leads to which reorganization?
- GPCRs
- Rac/Rho/cdc42 family (guanosine triphosphates), increase Ca2+
- Leads to reorganization of the cytoskeleton
Which leukocyte infiltrate predominates early in the response (6-24 hours) and later in the response (24-48 hours)
- Neutrophils are first and short-lived
- Monocytes are dominant in prolonged inflammatory rxns
What is the predominant leukocyte in Pseudomonas bacterial infections?
- Neutrophils dominate
- Will be continously recruited (exception)
Hypersensitivity reactions are dominated by which immune cells?
Activated lymphocytes, macrophages, and plasma cells
Agents that block _____ are among the most sucessful therapeutics ever developed for chronic inflammatory diseases?
TNF
*One of the major cytokines in leukocyte recruitment
What is the source of LTs?
Action?
- Mast cells, leukocytes
- Inc vascular permeability, chemotaxis, leukocyte adhesion and activation
What is the source of PAF?
Action?
- Leukocytes, mast cells
- Vasodilation, increased vascular permeability, leukocyte adhesion, chemotaxis, oxidative burst, de-granulation
What is the source of kinins?
Action?
- Plasma (made in liver)
- Increased vascular permeability, smooth muscle contraction, vasodilation, pain
What PGs or LTs are responsible for vasodilation?
PGI2 (prostacyclin), PGE1, PGE2, and PGD2
What PGs or LTs are responsible for vasoconstriction?
TxA2, LTC4, LTD4, LTE4
What PGs or LTs are responsible for increased vascular permeability?
LTC4, LTD4, LTE4
What PGs or LTs are responsible for chemotaxis and leukocyte adhesion?
LTB4, HETE
What PGs or LTs are responsible for bronchospasm (important in asthma), intense vasoconstriction, and increased permeability of venules?
LTC4, LTD4, LTE4
ROS are produced by the rapid assembly and activation of a multicomponent oxidase called?
Produces what?
- NADPH oxidase
- O2-* (superoxide anion)
In the respiratory burst within lysosomes and phagolysosome what are the series of rxns and the ROS produced?
How does the final product destroy microbes?
O2—(NADPH ox)—> O2-*–(SOD)—> H2O2 –(MPO)—> HOCl- (bleach)
- Destroys microbes through halogenation or by oxidation of proteins and lipids (lipid peroxidatio)
What are the 5 anti-oxidant mechanisms to combat ROS produced during the killing of microbes and protect the host?
1) SOD
2) Catalase: detoxifies H2O2
3) Glutathione peroxidase: detoxifies H2O2
4) Ceruloplasmin
5) Iron-free fraction of serum transferrin
Nitric oxide (NO) is produced by NOS, of which there are 3 different types, what are they?
How/when is each expressed?
- eNOS (endothelial-vascular tone) and nNOS (neuronal-NT) are constitutively expressed at low levels
- iNOS (inducible) kills microbes and induced by IFN-y or microbial products
NO reacts with what to produce what ROS that attacks lipids, proteins, and nuclei acids of microbes and host cells?
NO reacts with superoxide anion to makes ONOO
Lysosomal enzymes, if not controlled, can damage the host. Which antiproteases in the serum and tissue fluids serve as protection?
Major inhibitor of?
- α1-antitrypsin is major inhibitor of neutrophil elastase
- α2-macroglobulin
What is the function of major basic protein?
Cationic protein of eosinophils, that is cytotoxic to many parasites
Viscous meshwork of nuclear chromatin that binds and concentrates granule proteins such as antimicrobial peptides and enzymes is known as?
Neutrophil Extracellular Trap (NET)
The nuclear chromatin in the NETs, which includes histones and associated DNA, has been postulated to be a source of nuclear antigens in which diseases?
Systemic autoimmune diseases, particularly lupus
Which T lymphocytes play an important role in acute inflammation?
What do they produce?
Deficiency produces; increased susceptibility to?
- TH17 cells
- Produce IL-17, which induces secretion of chemokines that recruit leukocytes
- Deficiency = cold abscesses = more susceptible to bacterial and fungal infections
What is the source of Cytokines (TNF, IL-1, IL-6)?
Actions (both local and systemic)?
- Macrophages, endothelial cells, mast cells
Local: endothelial activation (expression of adhesion molecules)
Systemic: fever, metabolic abnormalities, hypotension (shock)
During termination of the acute inflammatory response which anti-inflammatory cytokines are released?
TGF-β and IL-10
Where is serotonin is found as a preformed vasoactive mediator where?
Primary function?
Effect on vasculature?
- Platelets and certain neuroendocrine cells in GI tract
- Primary function = NT in the GI tract
- Also a vasoconstrictor
What causes release of arachidonic acid from membrane phospholipids?
Phospholipase, mainly phospholipase A2
What biochemical signals activate phospholipase A2?
Increase in cytoplasmic Ca2+ and other kinases in response to external stimuli
What synthesizes eicosanoids (20-carbon fatty acids)?
Why are eicosanoids considered dynamic?
- Cyclooxygenases and lipooxygenases
- Bind GPCRs on many cell types and can mediate virtually every step of inflammation
What inhibits phospholipases?
Steroids
Prostaglandins are derived from where and via what enzyme?
Arachidonic acid via Cyclooxygenase
What is an inhibitor of inflammation arising from arachidonic acid?
What enzyme makes these?
- LXA4 and LXB4
- 12-lipoxygenase
What are the 3 key mediators of chronic inflammation?
- IL-12
- IFN-gamma
- IL-17
COX-1 and COX-2 are stimulated by?
Where is each expressed?
Functions of each?
- Stimulated by inflammation
- COX-1 constitutively expressed in most tissues; fluid/electrolyte balance kidneys, cytoprotection in the GI tract
- COX-2 is low or absent in most tissues; generates the prostaglandins involved in inflammatory response
What are COX-1/2 inhibitors?
- Aspirin and NSAIDs
- Inhibit prostaglandin synthesis
What is the precursor for leukotrienes?
Produced by what enzyme?
Action?
- 5-hydroxyeicosatetraenoic acid from 5-lipoxygenase
- Chemoattractant for neutrophils
Lipoxins are generated from arachidonic acid but have a different effect than do prostaglandins and leukotrienes, which is?
Inhibit neutrophil chemotaxis and adhesion to endothelium
Why might selective COX-2 inhibitors increase the risk of cardiovascular and cerebrovascular events?
- They impair endothelial production of PGI2, a vasodilator and inhibitor of platelet aggregation
- Leaving intact COX-1 mediated production by platelets of thromboxane A2, an important mediator of platelet aggregation and vasoconstriction
5-lipoxygenase is not affected by NSAIDs, and many new inhibitors of this pathway have been developed, such as Zileuton. What does this drug inhibit and is useful in treatment of?
- Inhibits leukotriene production
- Useful in tx of asthma
Corticosteroids are broad-spctrum anti-inflammatory agents that reduce trasncription of genes encoding?
COX-2, phospholipase A2, pro-inflammatory cytokines (IL-1 and TNF), and iNOS
Why is increasing consumption of fish oil effective in manipulating inflammatory responses?
- Polyunsaturated FA’s in fish oil are poor substrates for conversion to active metabolites by the COX and lipoxygenase pathways
- Better substrates for the production of anti-inflammatory lipid products
What are the 5 cytokines involved in acute inflammation?
1) TNF
2) IL-1
3) IL-6
4) Chemokines
5) IL-17
What is the source of IL-12?
Action in inflammation?
- DC, macrophages
- Increased production of IFN-gamma
What is the source of IFN-gamma?
Action in inflammation?
- T lymphocytes, NK cells
- Activation of macrophages
What is the source of IL-17?
Action in inflammation?
- T lymphocytes
- Recruitment of neutrophils and monocytes
What is the source of TNF?
Action in inflammation?
- Macrophages, mast cells, T lymphocytes
- Stimulates expression of endothelial adhesion molecules and secretion of other cytokines
What is the source of IL-1?
Action in inflammation?
- Macrophages, endothelial cells
- Similar to TNF, but greater role in fever
What is the source of IL-6?
Action in inflammation?
- Macrophages, other cells
- Acute phase response
Complement system is a collection of what kind of proteins?
Soluble proteins in the plasma
The critical step of complement activation is the proteolysis of which component?
Occurs via what 3 pathways?
- C3
- Classical, alternative, or lectin pathways